Tractor



y 398, 1936- G. w. HOPKINS, JR 2,043,697

TRACTOR Filed May 6, 1933 6 Sheets-Sheet 1 eg INVENTOR.

G. W. HOPKINS. JR

TRACTOR 6 Sheets-Sheet 2 Filed May 6, 1953 IN VEN TOR.

July 28, 1936.

6 Sheets-Sheet 3 INVENTOR.

RACTOR 3 m Jun 3 Y ww H MI w July 28, 1936. i G. w, HOPKINS, JR 2,048,597

TRACTOR Filed May 6, 1955 6 Sheets-Sheet 4 v EIE E IN V EN TOR.

July 28, 1936- G. w. HOPKINS, JR

TRACTOR Filed May 6, 1935 6 Sheets-Sheet 5 IN V EN TOR.

July 28, 1936- G. w. HOPKINS, JR 2,043,697

TRACTOR Filed May 6, 1935 6 Sheets-Sheet e II v E I 5.1. D

INVENTOR.

Patented July 28, 1936 UNITED STATES TRACTOR George w. Hopkins, Jr., San Leandro, Calif assignor to Caterpillar Tractor Co., San Leandro,

Ca1if., a corporation of California Application May 6, 1933, Serial No. 669,745

12 Claims.

The present invention relates to draft vehicles, such as tractors, and more particularly to the provision of drawbar means therefor. In operation, when a tractor is pulling a drawn vehicle,

5 the draft connection is under tension and hence tends to maintain itself in a straight line, whereby the greatest advantage can be obtained from a free lateral swinging drawbar. However, in backing the draft vehicle, or when the drawn load or vehicle tends to push the draft vehicle in going down-hill, the draft connection is'under compression, and if a'free lateral swing ing drawbar is used, tends to buckle. When this condition obtains, the draft force cannot be applied at the most advantageous angle and the drawn vehicle sometimes causes the tractor to turn, rather than the tractor controlling movement of the drawn vehicle. If a fixed drawbar is used, certain advantages are obtained when the drawbar is'under compression, but the ad vantages of a free lateral swinging drawbar during pulling of the drawn vehicle are lost. The present invention provides a drawbar which has a free lateral swinging movement when under tension forces, and is fixed in position when under compression forces.

It is an object of the invention to provide a self-centering drawbar for a draft vehicle. a Another object of the invention is [to provide a drawbar for a tractor having a flat planar portion with an opening therethrough'adapted' to receive a member on the tractorof'less cross' sectional size than the openirrgfl Another object of the invention is to provide a drawbar for a tractor having integral cam means for determining free lateral swinging movement of the drawbar during one type of operation of the tractor, and preventing lateral swinging movement of the drawbar during another type of operation. 7

Another object of the invention is toprovide a drawbar for a tractor having a fixed position and a free lateral swinging position relative to the tractor, and means engagingan end of the drawbar for controlling movement thereof" from one of said positions to the other.

Another object of the invention is to provide a simple and economical drawbar construction for a tractor whereby the drawbar is capable of free lateral swinging movement underloads placing tension thereon, and is held against lateral swinging movement underloads placing compression thereon.

Another object of the invention is to provide adrawbar construction for tractors providing a fixed position of the drawbar during one type of operation and a free IateralsWinging position thereof during another type of operation, said construction including 'means engaging said drawbar for effecting movement thereof and positioned entirely beneath the frame of the tractor.

Another object of the inventionis toprovide' a drawbar construction for tractors providing a fixed position of the drawbar during one type of operation and a free lateral swinging position thereof during another type of operation, said construction including cam surfaces and a member adapted for engagement wit-hisaid surfaces, said surfaces and the engaging portion of said member lying substantially in the horizontal plane of the drawbar. v I

Another object of'the invention is to provide a drawbar construction for tractors providing a fixed-position of the drawbar during one type of operation and a free lateral swingingposition thereof during another type of operation, said construction including cam means consisting of cam surfaces converging to an apex forming a socket and a single member adapted for engagement with said surfaces.

Another object of theinvention isto provide a drawbar construction for tractors providing a fixed position of the drawbar during one type of operation and a free lateral swinging position thereof duringanother type of operation, said construction including means pivotally mounted on the tractor and in response to movement'of said drawbar to prevent lateral swinging move mission case shown in phantom lines;

Fig. 3 is a vertical longitudinal section taken on the longitudinal center line of the tractor.

. Fig. 4 is a diagrammatic plan view illustrating the various positions of the drawbar.

Fig. 5 is a diagrammatic plan View of the second form of the invention.

Fig. 6 is a diagrammatic plan view of the third formof the; invention. A

. according to the instant invention with the transmechanisms H. a

trolled through steering clutch control levers I2,

7 is a diagrammatic plan view of the fourth form of' the invention. 7

Figs. 8,9, and i0 illustrate the fifth form of the r invention. 1 -Fig. 8 is a plan view.

'Fig. 9, is a side elevation. e a

Fig. 10is a detailed view taken on the line Ill-l0 in Fig. '8.

Description of mechanism The first form .of the invention,.illustrated in Figs. 1-4;,is disclosed as embodied in a tractor of the track-type, including main frame or body portion l0 (Fig. 1) comprising the transmission case, supported upon a pair of endless track Operation of the tractoriscongear shift lever l3 and brake pedals I4 at the operators station, rearwardly of power plantl6.

The drawn vehi'clemay beof ,any'suitable type,

t and is shown 'as V a road grader,-. which includes frame I! havingrear. supports l8.and front support's-l9; Draft pole 2| of the drawn vehicle is 7 pivotally connectedby pin 22 to drawbar 23 of the' tractor."

9 The'drawbar is mounted for free lateral swing.-

' ing movement in one relatively adjusted position with'respect to thetractor when pulling the drawn I vehicle, and upon reverse movement of the tractor',*or when thetractor is pushed by the drawn vehicle', is moved relative to thetractor to a fixed position to facilitate maneuvering of the vehicle train in such operations. To accomplish'thispurpose; meansare provided on the transmission case and entirely therebeneath engaging the drawbar and adapted to hold thedrawbar against lateral swinging movement when compression is placed movement when the drawbar is under tension. Drawbar 23' (Figs; 2 and .3) is formed at its front end with slot 24 engaging pivot means com-, prising pin 26' secured in spaced walls 21,28 of bracket'29, which is secured to pad 3 I (Fig. 1) in' tegrally formed with transmission case 10,; by screws'32. Said bracket 29. (Figs. 2 and3) guides the front end of drawbar 23, and provides mount- 7 ingmeans for drawbar pivot pin 26, which transmits draft forces thereto when. the drawbar is in free' lateral swinging position. V f

The rear end'of drawbar 23 (Figs. 2-and 3 is guided andbraced by vertically spaced plates 36 t having spacer plates 31 (Figs. land 3) secured therebetween ateach sid e. Plates 36, 3l-'(Figs. 2 and 3) are mounted as a unit on transmission case [0 by brackets 38 and screws 39;

Intermediate its ends drawbar 23 is apertured' to provide opposite, rearwardly converging cam surfaces 4|, .42 adapted for cooperation with pin 43 securedin boss 44 (Fig. 3) integral with'transmission case l 0. Cam surfaces 41,142 convergejto apex 45' -.(Fig.'2) providing a 'socketfor pin 43.

Said pin 43 provides; draft transmitting means when the drawbar is moved relatively to the trac- 'tor when placed under compression, and-also serves as means "for limiting lateral "swinging movement ofthedrawbar when said drawbar is under tension,i. e; in'thezposition shown in Figs." 7. 1-3. Said pin43 also serves to preventoscillation '1 :of drawbar 23 abou'tfpin126 when the drawbar is under, compression "ina manner about" to be described;

F'gr4 illustrates'various positions of drawbar 23 with respect to transmission case [0, saiddrawbarbeing shown in full lines in its fixed position with respect to the tract0r.----When the forces orr' lines in Fig. 4.

the drawbar change from tension to compression,

one of cam surfaces 4 l 42 engages pin 43 if draw bar 23 is displaced laterally from its central position, serving as'means for moving the drawbar relatively to the tractor from its free lateral swinging position to its fixed position, where pin 43 engages said drawbar at apex 45 of 0am surfaces 4|, 42, pin 26 remaining in slot 24. The fixed position of the drawbar is indicated in full The phantomline'position indicates the extreme righthand position ofthe drawj bar, pin 43 engaging said drawbar at the respective outer ends of cam surfaces 4|, 42. It is believed obviousthat, if the drawbar is in any laterally displaced position,'and is placed. under compression, it is moved to the fixed position 7 thereof.

.Thus it is seen that the drawba is mountedfor .free lateral swinging movement under a load placing tension thereon, and isplaced automatically in ajfixedf'position underloads placing comprese sion thereon) It is to be noted that the means for positioning and'maintaining the. drawbar in a fixed position when under compression are po-' sitioned entirely. beneath the transmission case or frame .of the tractor. This feature is very. advantageous as it provides a simple and compact structure which is economical'to manufacture and.

'assemb1e',;and which does not interfere with the mounting of auxiliary attachmentslon'thetrac:

tor. The above advantages are also obtained-in part by placing the drawbar engaging surfaces of the positioning and maintaining means in sub- 7 stantially. the same horizontal: plane as the drawbar. j r

In the second form of'the invention, drawbar 6| (Fig. 5) shown in full lines in its fixed posi-.

on transmission case l0, similarly to pin 43 (Fig.

' 3). At its rear end, drawbar 6| may be supported tion,-is provided intermediate its ends with longitudinal slot .62, engaged by pin 63 providing pivot .means for the drawbar. 'Pin' 63' may be mounted on transmission case fll'similarly to. drawbar 23.

At its front. end, drawbar 6| has roller 64 adapted to engage plate 65 at apex 66 of forwardly con- 7 verging cam surfaces 61, 68, when said drawbar is under compression; preventing, with pin 63, any

lateral swinging movement thereof ,7

When drawbar :61 is, placed. under 7 tension,

movement thereof relative to the tractor occurs from its fixedposition to its free lateral swinging position, pin 63 engaging the front end of slot 62.

. This condition is illustrated by the phantom use positions; roller64 engaging one of cam surfaces 5'1, 68,. in the extreme lateral positions of the It is believed obvious that, upon initial drawbar; placing,ofgcompriession on the drawbar, one of cam surfaces 61,158 isengagedby roller 64, if the drawbar'is displaced from its central position, and. the drawbar is, moved relatively to the tractor to its fixed position. It is to be noted that in this form of the invention the means for.

positioning andmaintaining thedrawbar in a fixed position when under compression is positioned entirely beneath transmission case I 0, and,

that the drawbar engaging surfaces of the positioning: and maintaining means lie substantiallyf in'the horizontal plane of the drawbar; one of said means engaging an: end of the drawbar.

The above described formsof the invention are preferred due to the simplicityand compactness oftheirstructure which lends itself to economy a of manufacture and assembly; The followingdescribedforms of the invention, while more complicated in i stru :ture,- retain certain Y of the ad is mounted'for movement relative to the tractor vantages .noted in describing the first and second forms of the invention. r c

" In the thirdform of theinvention (Fig. 6), pivot means are provided on the frame having sliding, pivotal engagement with the drawbar, and automatically operable levermeans are provided on the frame movable to engage the drawbar at spaced points to prevent lateral swinging movement thereof under loads placing compression thereon. DrawbarII is provided at its front end with longitudinal slot I2 engaged by pivot means comprisingpin 'I3, mounted on transmission case I similarly to pin ,43 of the first described form of the invention. Atits rear end, drawbar II may be supported on case I0 similarly to said described drawbar 23.

Intermediateits ends drawbar II is provided with integral vertical lug'M'having a flat front face adapted for contact by curved front ends I6, II of levers I8, I9, Said levers I8, I9 are pivoted on pins BI, 82 on crankcase I0, and have rollers 83;mounted.in there'ar ends thereof adapted .to contact the sides ofdrawbar II in the fixed positions thereof.

Drawbar II is illustrated in full lines in its fixed position which it occupies when under compression. In this position, ends I6, 11 of levers I8, I9 are engaged by lug I4 on drawbar II', urging rollers 83 against the respective sides of the 'drawbar to prevent lateral swinging movement thereof. In this position, pin I3 engages the rear end of slot 12. The Various parts assume this position in response to movement'of the drawbar relative tothe tractor when the load on the drawbar changes from tension to compression. When the tractor is pulling the draft vehicle, and the drawbar is under tension, said drawbar is moving relatively to the tractor to its free lateral swinging position illustrated in phantom lines in Fig. 6. In the free lateral swinging position, pin I3 engages the front end of slot I2, and lug I4 is moved rearwardly to permit free oscillation of levers I9, I9, lever 'I8 being illustrated in its extreme outward position in phantom lines in the figure,

Thus it is seen that the drawbar is maintained in a fixed position under loads placing compression thereon, and is movable relative to the tractor from such fixed position to a free lateral swinging position under loads placing tension thereon. It is to be noted that the means for positioning and maintaining the drawbar in a fixed position are located entirely beneath the frame of the tractor.

The fourth form of the invention is illustrated in Fig. '7 and is generally similar to the form of the invention illustrated in Fig. 6, the operation of the drawbar and the mounting means therefor being substantially the same. Drawbar 9I has slot 92 adjacent its front end engaged by pin 93 on transmission case I0. At its rear end said drawbar is provided with integral vertical extension 94 engaging-by levers 95, 96 pivoted at 91, 98 on transmission case I0. It is not believed necessary to describe the operation of the form of the invention illustrated in Fig. 7 as it is identical with that described in connection with Fig. 6. It is to be noted that in this form of the invention, also, the means for positioning and maintaining the drawbar in a fixed position is located entirely beneath the transmission case or frame of the tractor, the means engaging an end of the drawbar.

Figs. 8-10 illustrate a fifth form of the invention. In this form of the invention, the drawbar from .a fixed. position to a free lateral swinging position, the mounting means including cam means movably mounted on the transmission case and responsive to movement of the drawbar under loads placing compression thereon to move said drawbar toits fixed position.

. Drawbar .IOI (Figs. Sand 9) is provided at its front end with longitudinal slot I02 engaged by pin I03 mounted in bracket I04 (Fig. 9) which is secured to .pad I06 integralwith transmission case I0. Said pin I03 providesthe pivot point of the .drawbar and serves as draft transmitting means from the tractor to the drawbar. Bracket I04 is similar to bracket 3| of the first form of the invention. Adjacent its rear end, drawbar IOI isesupported and guided by vertically spaced plates I01, I08 secured to transmission case I0. Forwardly of plates I01, I08, drawbar. IOI is provided with integral .lateralextensions III which are engaged by forked front end I I2 of cam lever I I3, pivoted on shaft I Mon transmission case I0. The rear arm of lever II3 (Figs. 8 and 10) extends laterally with respect to transmission case I0 and is provided with opposite similar cam surfaces II6, II'I converging upwardly to socket II8. Cam surfaces H6, H1 and socket II 8 are adapted for engagement with roller II9 rotatably mounted on drawbar IOI' adjacent the rear end thereof. V

Drawbar IOI is illustrated in full lines in Figs. 8 and 9 in itsfixed position, i. e., in its most forward position with respect to the tractor where it is held against lateral. movement by the engagement of roller I I9 in socket I I8. The phantom line position of drawbar ml in Fig. 9 illustrates its free lateral swinging position where lugs III no longer maintain cam lever H3 in the full line position illustrated in Fig. 9 but permit oscillation of said lever in a clockwise direction in response to lateral movement of drawbar IOI, roller I I9 engaging either of cam surfaces I I6, In. It is believed obvious that upon movement of drawbar IOI- from its free lateral swinging position to its fixed position, lever II3v is effective irrespective of the laterally displaced position of the drawbar to move said drawbar to its central fixed position. where itis maintained so long as compression is placed thereon.

I, therefore, claim as my invention:

1. In a tractor, a frame, a drawbar, pivot means on said frame having a relative sliding, pivotal engagement with said drawbar, and lever means movably mounted on said frame engageable with said drawbar at spaced points, said pivot means and said lever means being responsive to relative movement of said drawbar and said frame to pro- 7 vide a free lateral swinging position for said drawbar and a fixed position therefor on said tractor.

2. In a tractor, a frame, a drawbar relatively movable longitudinally of said frame when the load thereon changes from tension to compression, and vice versa, pivot means on said frame having a relative sliding, pivotal engagement with said drawbar, and lever means on said frame and engageable with said drawbar, said lever means and said pivot means being responsive to relative longitudinal movement of said drawbar on said frame to provide free lateral swinging movement of said drawbar under loads placing tension thereon, and to prevent lateral swinging movement of said drawbar under loads placing compression thereon.

3. In a tractor, a frame, a drawbar, pivot means on said frame having a 'relativefsliding, pivotal engagement withsaid drawbaniandflevr means movably mounted onzsai'd frame 'enga'geable' with said drawbar at spaced pointasaid pivot means and said lever means being positioned entirely V beneath said frame and being responsive to i'e'la-e tive'movement of-said drawbarr and saidframefto provide a freelateral swingingipo'sition for said drawbar and a fitted position therefor on said tractor. V-

. In a draft vehicle, a drawbar mounted to shift longitudinally with respect to'sa'id vehicle when the forces imposed .upon said drawbar change from tension to compressiongand means for: locking the drawbar against lateralimove ment, comprising cam members movable bysaid drawbar upon shifting movement thereof, a cam engaging surface on said drawbar, and portions onsaid cam members automatically engagedby 20 said drawbar surfaceiipon shifting of said drawbarjx I; i

In a tractor, a frame, a drawbar, pivot means on said frame having relative sliding, pivotal en-.

Tgagement with said drawbar at an end thereof, a and a pairrof opposite members movably mounted on said frame; each of said members being engageable with said drawbar at spaced points intermediate-the length thereof in response to relaj tive movement of said 'drawbar on said frame under'loads placing compression thereon to prevent lateral swinging movement thereof J I ,6. Ina'tractor, a frame, a drawbar, pivot means on said frame having relative sliding, pivotal en- 7 gagement withsaiddrawbar adjacent an end 4( 7 V p a V swinging -movement thereof; r

" thereof, and a pair of opposite'me'mbers movably mounted'on' said frame and engage'able with said drawbar'at said end and at'a point intermediate the length thereof in response 'torelative movement of said drawbar on said frame under loads placing compression thereon to prevent lateral e '7; In a' tractor, a frame, a drawbar mounted for relative movement on said frame, pivot means on said frame havingi a sliding, pivotalengage- -ment with said drawbar, and cam means movably mounted on said frame, said cam meansrbeing movable to engage said drawbar to prevent lateral swinging movement thereof in response to relation 'of saidlevers'upon said endwise movement tive movement of said drawbat on'saidrrameiim der loads placing compressionion saidtdrawbar;i 8. In a draft vehicle, a drawbar, means mounta ing' said :draWbar for swinging and endwlse movement, and movable means on said vehicle includ- 31.5 mg a pivotally' mounted member engaging said drawbar for holding said drawbar against swing ing movement when said drawbar is subjec'tedto compression forces, said movable means beingopf erab-le by said endwise movement of said drawbar. 1 v

9. ma draft vehicle, a drawbar, means mount- 7 ing said drawbar forf swinging and endwise movement on said vehicle, and cam means mbvably mounted on said vehicle and engaging sai d draw bar, fsaid cam means being movableeto prevent 1'55 7 said swinging movement thereof in response" to said endwise movement of said drawban' 5;

'10. In a draft vehicle, a d'rawbaif; means mounting said drawbar for swinging and endwise movement on said" vehicle, "a pair of leversjon opposite sides of said dralwbarjmeans pivotally V moi'inting said levers on said vehicle' andmeans on said drawbar adapted for simultaneous 'engagement with one pair of adjacent ends 'of said levers upon endwi'se movementof said drawbar, 5

the other pair of adjacent ends of said levers be; ing engageable with said drawbar to prevent swinging movement thereof in response to actuaof said drawbar. I 7 r 11. In a draft vehicle, a idrawbar, means mounting said 'drawbar for swinging and endwise movement on said vehicle; and 'levermeans move ablymounted on said frame and engaging" with} said drawbar, saidlever means being operable by endwise movement of said"drawbar to prevent I tion for said drawbar and a fixed position therea 

